Abstract: One exemplary embodiment is method of operating an electrically excited synchronous machine (EESM) system. The system includes a converter operatively coupled with one or more stator windings, an exciter operatively coupled with one or more field windings, a controller operatively coupled with the converter and the exciter, and a power supply operatively coupled with the converter and the exciter. The controller determines whether a power supply fault condition exists and whether EESM system is operating in a motor mode or a generator mode. If the power supply fault condition exists and the EESM system is operating in the motor mode, entering one of a motor ride through control mode and a motor controlled braking control mode If the power supply fault condition exists and the EESM system is operating in the generator mode, entering one of a generator ride through control mode and a generator controlled braking control mode.

Abstract: A electromagnetic machine system includes a rotor and a stator positioned about the rotor. A current injection mechanism is coupled with windings of the stator and structured to inject electrical currents therein so as to change a flux distribution of a magnetic field produced by the stator. The injected currents may be harmonic currents. The rotor further includes an inductor positioned to interact with the magnetic field when the flux distribution is changed, to produce an electrical excitation current for exciting windings in the rotor. The machine system may be a synchronous motor or generator, and may be brushless. Applications of the current injection strategy to direct torque control and vector control are also disclosed.

Abstract: Technologies for reducing peak fault output current in a DC power generation system include a generator having a reduced damper winding and a controller to control a rectifier array to generate a DC power output. In some embodiments, the generator may have no damper windings, may have damper windings including a reduced number of damper bars, and/or may have damper windings having separated end ring mounts for each damper bar. The controller is configured to control the rectifier array so as to reduce oscillations of the DC output that may be due to the reduced damper windings. To do so, the controller is configured to generate the control signal based on an oscillation component of the DC power output. For example, the controller may generate an oscillation correction signal based on the DC power output and adjust a firing angle set point of the rectifier array based on the oscillation correction signal.

Abstract: One exemplary embodiment is method of operating an electrically excited synchronous machine (EESM) system. The system includes a converter operatively coupled with one or more stator windings, an exciter operatively coupled with one or more field windings, a controller operatively coupled with the converter and the exciter, and a power supply operatively coupled with the converter and the exciter. The controller determines whether a power supply fault condition exists and whether EESM system is operating in a motor mode or a generator mode. If the power supply fault condition exists and the EESM system is operating in the motor mode, entering one of a motor ride through control mode and a motor controlled braking control mode If the power supply fault condition exists and the EESM system is operating in the generator mode, entering one of a generator ride through control mode and a generator controlled braking control mode.

Abstract: A synchronous machine system comprising a synchronous motor including a stator, stator winding, rotor, and field winding; an AC power supply circuit structured to transmit current to or from the stator winding of the synchronous motor at a controlled frequency and transmit current to or from a power source at a controlled frequency; a DC exciter unit structured to receive power from a power source, convert the received power to DC power at a desired voltage, and supply the converted power across a DC bus to the field winding of the synchronous motor; and an energy storage circuit coupled to the DC bus of the DC exciter unit having at least one ultracapacitor, and structured to receive power from a power source, to charge the ultracapacitor, and to provide power to the field winding of the synchronous motor following a power failure.

Abstract: Technologies for reducing peak fault output current in a DC power generation system include a generator having a reduced damper winding and a controller to control a rectifier array to generate a DC power output. In some embodiments, the generator may have no damper windings, may have damper windings including a reduced number of damper bars, and/or may have damper windings having separated end ring mounts for each damper bar. The controller is configured to control the rectifier array so as to reduce oscillations of the DC output that may be due to the reduced damper windings. To do so, the controller is configured to generate the control signal based on an oscillation component of the DC power output. For example, the controller may generate an oscillation correction signal based on the DC power output and adjust a firing angle set point of the rectifier array based on the oscillation correction signal.

Abstract: A synchronous machine and related systems include a stator and rotor separated by an air gap. The rotor includes a rotating DC power supply coupled to exciter windings disposed adjacent the air gap. Power from air gap harmonics, including air gap slot harmonics induce current in the exciter windings, which is rectified and supplied to the rotor field windings. In operation, a desired current level in the rotor field windings can be achieved through control of the DC power supply or superposition of harmonics into the stator winding current which induces the prescribed current in exciter windings.

Abstract: A permanent magnet machine with a hybrid cage and methods for operating same are disclosed. According to one aspect, the subject matter described herein includes a rotor and hybrid cage for an electrical machine, the rotor comprising a rotor body having a central axis and including a plurality of permanent magnets positioned to create a plurality of rotor magnetic poles distributed around a peripheral surface of the rotor. The rotor also includes a hybrid cage that includes conductive loops around each of the rotor magnetic poles, where the conductive loops are controllable to form a closed circuit or an open circuit around each of the rotor magnetic poles.

Abstract: An electric machine having a stator surrounding a rotor with an air gap therebetween. The stator has slots in its inner margin for accommodating stator coil windings. Stator teeth defined by the slots have irregular shapes to modify a variable flux flow pattern in the air gap to reduce harmonic torque components with minimal effect on an average value of rotor torque.

Abstract: An electric machine having a stator surrounding a rotor with an air gap therebetween. The stator has slots in its inner margin for accommodating stator coil windings. Stator teeth defined by the slots have irregular shapes to modify a variable flux flow pattern in the air gap to reduce harmonic torque components with minimal effect on an average value of rotor torque.